Crushing devices, such as cone crushers and gyratory crushers, are typically used to crush rock, ore or minerals. Crushers may form a circuit of a process configured to crush material from a first size to a smaller size. After the material is crushed, the material may be moved to a grinding circuit for grinding the material to an even smaller size.
One type of crushing device that is commonly used is a cone crusher, which typically breaks rock by squeezing the rock between an eccentrically gyrating spindle and an enclosing concave hopper. As rock enters the top of the cone crusher, it becomes wedged and squeezed between the mantle and the bowl liner or concave. Large pieces of ore or rock are broken and then fall to a lower position (because they are now smaller) where they are broken again. This process continues until the pieces are small enough to fall through a narrow opening at the bottom of the crusher. The crusher head of cone crushers is typically guided by an eccentric assembly to actuate movement of the head for crushing material. It can be appreciated that there are generally two types of cone crusher designs. One in which the concave hopper can be adjusted in position relative to the gyrating spindle to adjust for wear and change product size. The other type is designed such that the gyrating spindle can be raised and lowered.
Gyratory crushers are also well established machines that are used for crushing rocks, ore, and other materials. A gyratory crusher is a cone crusher designed for very large feed. The gyratory crusher is usually the first stage of size reduction equipment in a mining operation. They are very large and their basic structure comprises a bowl shaped as a cone with the wider end of the cone near the top of the crusher. A conical head assembly is located on the axis of the bowl, and the head assembly is oriented so that its smaller dimension is at the top of the crusher. To perform the crushing action gyratory motions are applied to the conical head assembly.
In the typical gyratory crusher, large material is fed into the top of the crusher between the large opening of the bowl and the small end of the head assembly where the volume is largest. The gyration of the head assembly is furnished by an eccentric assembly, the rotation of which is driven by a gear. Vertical support and minor vertical adjustment of the head assembly is furnished by a hydraulic support assembly. These parts are typically located at the bottom of the crusher, and more specifically they are located at the bottom of the conical head assembly. The gyration applies forces that crush the pieces of material, and they fall lower into the reduced space within the bowl as they are reduced in size. Ultimately the material leaves the crusher through openings at the bottom of the crusher.
Gyratory and cone crushers typically have used large bevel gears as the main drive for the eccentric drive. However, large bevel gears are expensive, and typically large bevel gears have a long lead time to manufacture. In addition, it can be appreciated that large bevel gears are difficult to set up for optimum operating condition. Large bevel gears are also designed to be operated at fixed center distances. Since the eccentric assembly typically operates within a bushing with an operating clearance, the bevel gear will not operate at fixed centers and as such performance is not optimum. The large bevel gears also have limited suppliers and require master sets for interchangeability. Large bevel gears are also limited in the reduction ratio (speed change) they can achieve.
Accordingly, it can be would be desirable to replace the traditional bevel gear assembly on the eccentric drive with a small gearbox assembly utilizing a parallel axis main gearset, which can provide better performance, simplify the manufacturing process, provide reduced lead time for manufacturing thereof, can be manufactured by an increased number of manufactures, competitively priced and provides for a simplified installation and adjustment. In addition, master sets will no longer be needed. Also, further savings can be realized in the motor selection due to increased reduction ratios and correspondingly increased motor speeds.